Registeration
 

How do i make it so people that have illegal chars like (") and etc.. not be able to register without manually inserting all the symbols..

I just want them to be able to enter numbers+letters.

Under "User Registration Options" - Username Regular Expression - enter this:

This will allow use of all letters a through z or A through Z, and numbers 0 through 9 along with allowing the use a space in the name. If you don't want them to be able to insert a space, remove the space after 9 in the code above.